Knock on doors in this Raleigh suburb and identify residents opposed to President Obama's health care law and his stewardship of the economy — all part of an ambitious voter-outreach campaign by Americans for Prosperity, a non-profit backed by billionaire brothers Charles and David Koch that is emerging as one of biggest outside forces of the 2012 election.

The Kochs, who own an oil, chemical and textile conglomerate that Forbes magazine pegs as the nation's second-largest private company, have become the country's leading figures of libertarian activism. The Koch duo (pronounced "coke") has injected millions into an array of foundations, think tanks and political groups to spread their small-government, anti-regulation philosophy, which their critics argue matches their economic interests.

Obama targeted them in the first TV ad of his re-election campaign as "secretive oil billionaires." And Hollywood has joined in: A new comedy, The Campaign, features the fictional Motch brothers, business titans who try to rig the election to advance their corporate agenda.

"It's almost like Kochs have created an alternative to the Republican Party that pushes their brand of conservatism — an economy with less regulation and one in which the government intervenes far less than it does now," said Bill Allison of the non-partisan Sunlight Foundation, which tracks political money. "I don't think we've seen anything like this before, and a lot of it is under the radar."

Americans for Prosperity (AFP) has been at the forefront of the libertarian attacks on Obama, blistering him with $25 million worth of commercials this month. The first round focused on the nation's rising debt and call for Obama's ouster. AFP officials stress, however, that their goal isn't to elect Democrats or Republicans but to educate voters on the candidates' positions and build a cadre of activists willing to hold elected officials accountable after Election Day.

The group is well on its way to amassing more than $100 million this year, AFP President Tim Phillips said, but he notes that less than half of the money will be spent on ads. Instead, most of the activity will happen far from the spotlight as the group taps an army of 2.1 million activists to reach voters in swing states such as North Carolina, which Obama won by 14,177 votes in 2008 and where he will be renominated for the presidency next month at the Democratic National Convention in Charlotte.

AFP's goal: to reach about 8.5 million voters in more than a dozen battleground states. The group's ramped-up activity highlights the ways independent political groups of all stripes and political allegiances — often funded by a handful of wealthy donors — are racing to shape national policy. And it points to an aggressive expansion by Republican independent groups into voter-mobilization efforts that were once the province of candidates and the parties.

Know the voter

AFP's voter-canvassing is a precise operation — distilling information culled from a massive voter data warehouse, also created with the Kochs' financial backing. Conservatives say they took their cue from Democratic-aligned groups, who used a vast voter databank funded with help from billionaire financier George Soros to identify and turn out voters in 2004 and again in 2008.

The conservatives' data-gathering operation, called Themis for the Greek goddess of divine order, amasses information on millions of Americans and allows political strategists with AFP and other like-minded groups to pinpoint potential supporters and bombard them in person, via the phone and Internet with personalized messages.

"Our geo-targeting looks at everything from voting data to Census data to consumer-purchasing information," Phillips said. "We know their magazine subscriptions. In some cases, we know the websites they prefer to surf."

Launched in 2003, AFP and its sister organization, the Americans for Prosperity Foundation, have grown in size and influence, now employing 200 people in 31 states.

AFP helped organize some of the raucous protests at 2009 congressional town-hall-style meetings to oppose Obama's health care plan and rallied its supporters in recent years to oppose Democratic-backed legislation that would have created a cap-and-trade system to reduce greenhouse-gas emissions. On that day in late June when the Supreme Court upheld the 2010 health care law as constitutional, the group immediately announced a $9 million ad campaign in 12 presidential swing states to slam the law as one of the "largest tax increases in history."

Little is publicly known about the precise sources of its funding. Americans for Prosperity and its foundation reported combined revenue of nearly $39.6 million in 2010, according to the groups' tax returns. David Koch is the foundation's president.

Americans for Prosperity is a non-profit "social welfare" organization that can take unlimited money, but does not have to publicly disclose the sources of its money. (That's in contrast to super PACs — committees that can raise and spend unlimited amounts, but must disclose contributors.)

Phillips declined to reveal funders, saying such disclosure would have a "chilling effect" on donors.

Tar Heel State opening

North Carolina — one of nine states won by President George W. Bush in 2004 that shifted to Obama four years later — is home to one of AFP's busiest state chapters with nearly 140,000 activists.

Obama, too, has a robust activist network in the state, where he became the first Democrat to carry North Carolina since Jimmy Carter's victory in 1976. His campaign has opened more than 40 offices here and installed hundreds of voter-registration boxes in barbershops and beauty salons.

But Obama's narrow win in 2008 came against a Republican ticket so cash-strapped that "it was virtually impossible for anyone here to get a McCain-Palin yard sign," said Dee Stewart, a GOP strategist in Raleigh.

The picture is markedly different this year. Republican presumptive nominee Mitt Romney and the Republican Party out-raised Obama and Democrats in July — the third month in a row — and Romney has opened 20 offices in the state. Further adding to Democrats' worries: Jobs figures released last week show unemployment in the state climbed to 9.6% in July, topping the 8.3% rate for the nation.

Dallas Woodhouse, AFP's North Carolina director, said he believes support for Obama has waned in the white, working-class suburbs that sided with him four years ago. "They are contending with high food prices, big gasoline bills," he said, "and their young adult children with college degrees are stuck at home with Mom, flipping burgers for a living."

Finding those who 'disapprove'

Back in Garner on a recent Tuesday evening, the small band of Americans for Prosperity volunteers takes to the streets to find some of those voters.

At one stop, George Hansen, 74, tells 30-year-old volunteer Amy Bryson that he's deeply worried about the economy. Hansen's adult daughter works at a pet store and struggles with her mortgage, but she can't find a better-paying job, he said. He voted for Obama but isn't sure whom he will support in November.

A few blocks away, volunteer Peter Morley, 69, reads his survey questions to Recia Long as she sits on her front porch, smoking a cigarette. Obama's economic policies have had no impact, she responds. How does she feel about the 2010 health care law? "Disapprove," the 63-year-old retiree answers.

With a few touches on the tablet's screen, Morley logs her responses. She's a likely target for follow-up communication.

Josette Chmeil, 44, relishes her role with AFP. The energetic ex-New Yorker who now runs her own business as a professional organizer in Durham, N.C., said she is appalled by what she views as government intrusion into personal matters.

"New York is now a nanny state that's governing the size of soft drink you can buy," she says, referring to Mayor Michael Bloomberg's drive to ban the sale of super-size sugary drinks. "It wasn't like that 20 years ago."

She's one of AFP's most active Raleigh-area volunteers, devoting as many as seven hours a week. During the canvassing, she strides quickly up concrete driveways despite 90-degree heat and swarming gnats. Most of her assigned residents decline to take the survey.

"It's not frustrating," she says later. "If I knock on 20 doors and have one person I can have a dialogue with and change their perception, that's success."